The present invention relates to an apparatus, and a method, for removing bead wire from discarded vehicle tires. More particularly, the invention relates to an automatic debeading apparatus and an automated debeading method, requiring a minimum of manual intervention, in which the tires are fed one-at-a time to a debeading chamber, the bead wire is removed from the tires, and the debeaded tire carcasses are then discharged from the debeading chamber.
Each year, approximately thirty to forty million new passenger and light truck tires are manufactured in the United States alone. In past years it has not been economically feasible to recycle the discarded tires, due primarily to the cost of handling the tires and the absence of a market for the recycled tire material. As a consequence, many of these tires have been relegated to landfills or have been piled on both public and private land. The tire piles present a health problem, as they breed rodents and other vermin. The tire piles are also unsightly and are frequently the site of fires that are very difficult to extinguish. Recently, many states have passed laws prohibiting tire piles as well as the discarding of tires anywhere other than in authorized depositories. Most landfills do not accept tires unless they have been split around the tread center, because unsplit tires occupy too much volume and tend to float to the surface.
A vehicle tire includes a rubber casing that seals against the wheel rim and is generally reinforced with a non-metallic cord. For most tires, onto this casing is placed a wide band of two layers of closely spaced fine wire which underlies a thick outer layer of tread rubber as a wearing surface. In order to prevent the casing from pulling free of the wheel rim, bead wire consisting of several relatively heavy gauge wires is vulcanized into the tire casing on each side where it mounts to the rim. In most cases, the bead wire is made of four wires wound on a mandrel to make two to three layers prior to insertion in the tire. One manufacturer includes one additional wire of even heavier gauge in with the winding. A good tire is an item which is virtually indestructible not readily biodegradable.
There are several known uses for recycled scrap tires. Rubber bums clean at the temperatures found in modem furnaces with a heat value slightly higher than that of coal. For this reason, whole tires, along with iron, are added to cement kilns. However, this use of scrap tires is limited. Some grate-type furnaces can also bum whole tires but the heavy bead wire in the tires frequently causes problems in the grates.
Shredded tires in pieces about two inches square find a greater use as fuel but the bead wire again causes problems in the furnace grates. Additionally, the heavy bead wire must be sheared approximately fifty times by the shredder. Fine wire in the tread belts is sometimes not acceptable to be burned, so the material from the shredder must be magnetically separated before burning. At this stage, bead wire removal provides up to approximately forty percent more wire-free rubber.
Shredded tires are also fed through reduction mills where the rubber is mechanically reduced in size and wire is worked clear. By magnetic means, the free wire is removed from the rubber. After several stages of milling and separation the wire-free rubber is screened into various meshes. This is known as crumb rubber. Larger pieces are used as a covering for playgrounds or processed into other uses such as for a running track.
Finer meshes find a variety of uses in the manufacturer of articles such as hoses, belts, buckets and building blocks. As an additive to asphalt in road surfaces to extend their life, this rubber has a very large potential usage.
Whether tires are used as fuel or to generate crumb, the removal of the bead wire has the advantage of greatly expanding blade life in the shredder and reduction mills. When the rubber is used for fuel, grate life and maintenance are extended and the high-grade steel in the bead wire is available to be sold for additional revenue.
An apparatus for debeading tires, disclosed by Uemura in U.S. Pat. No. 3,838,492, employs a hooked bead puller that is movable through a cruciform die opening and through the bead opening of a tire so as to engage the bead of the tire. The slots in the die opening will accommodate the hook of the bead puller and the bead wires grasped by the hook. The rubber encasing the bead wire cannot pass through the die opening and is stripped away as the hook is retracted through the die opening. Debeading operations carried out using the Uemura apparatus are considerably labor intensive and time consuming. Tires to be debeaded are placed in the apparatus manually one-at-a-time. A debeading operation can remove the wires from just one of the tire beads at a time. Removal of the wires from the other bead requires positioning the tire with the other sidewall confronting the die opening and repeating the just-described operation of drawing the bead wires through the die opening. Because the force required to remove the wires from a tire bead is considerable, a firm engagement of the hook with the tire bead, to ensure grasping of the wires by the hook, is essential. In the Uemura apparatus, the weight of the tire presses the bead against the extended hook. The pressure between the hook and the tire bead produced by the weight of the tire alone does not always result in a secure grasp of the wires by the hook. Also, the removed bead wires remain on the upwardly open hook and must be removed before another debeading operation can take place.